Cliona. Z. ASCIDIOIDA. 305 



face is porous or cellular, even, roughish, the pores roundish or pen- 

 tagonal, distinct and separate, but not arranged in rows, or in any re- 

 gular fashion ; the interior is irregularly cellular, and earthy. — None 

 of the mineral acids have any effect on this substance, nor does it absorb 

 water like a sponge, but when dropt into a glass of water, it sinks to 

 the bottom and lies there unaltered. No siliceous nor calcareous spi- 

 cula enter into its structure, but it seems to be entirely composed of 

 particles of sand cemented together with mud or clay. It has there- 

 fore no character of a proper polypidom, although the conformation 

 and regularity of its cells prove it to be the work of some gregarious 

 animal. 



41. Cliona, * Grant. 

 Character. Polypidom amorphous^ Jieshy, containing sili- 

 ceous spicula and perforated with ramified canals. — Polypes mi- 

 nute, retractile, placed in tubular papillce. 



1. C. CELATA. R. E. Grant, f 



Plate xlii. Fig. 5, 6. 



Cliona celata, Grant in Edin. New Phil. Journ. i- 78 ■ ii. 183, pi. 2, fig. 7, 



(the spiculum.) Flem. Brit. Anim. 516. Stark, Elem. ii. 421 



La Clione cachee, Blainv. Actinolog. 527. 

 Hab. In perforations of the shell of the oyster (Ostrea edulis) : 

 abundantly in the oyster beds at Prestonpans, off Inchkeith, and in 

 the roads of the Firth of Forth, Grant. 



This sponge-like zoophyte inhabits and fills up the worm-like holes 

 in old oyster-shells. The part which projects beyond the orifice 

 of the hole is papillary, about a line in height and about the same in 

 breadth, of a yellowish colour, tubular, and either closed or widely 

 open at the apex. In texture it resembles the Halichondria papil- 



' " I have termed this genus Cliona, (from KXitce, claudo), from its most ob- 

 vious and remarkable property of retracting and shutting the papilla when irri- 

 tated ; and the above described species, the only one I have met with, is named 

 celata, from its concealed and secure habitation within the substance of oyster- 

 shells." Grant. 



f Dr G. is a native of Edinburgh, where he received his education, and gra- 

 duated M. D. in 1814, when he was President of the Royal Medical Society. 

 His Thesis was " de Circuitu Sanguinis in Foetu." Shortly afterwards his at- 

 tention was turned to natural history ; and his researches into the nature of 

 sponges and zoophytes laid the foundation of that reputation which readily se- 

 cured him the chair of Zoology and Comparative Anatomy in the London Uni- 

 versity, on its first establishment, — a chair which he continues to fill with the 

 most distinguished ability. 



U 



